a(n) = (n-1)*Catalan(n).

Terms

a(0) =-1a(1) =0a(2) =2a(3) =10a(4) =42a(5) =168a(6) =660a(7) =2574a(8) =10010a(9) =38896a(10) =151164a(11) =587860a(12) =2288132a(13) =8914800a(14) =34767720a(15) =135727830a(16) =530365050a(17) =2074316640a(18) =8119857900a(19) =31810737420a(20) =124718287980a(21) =489325340400